Such developing apparatus is used for example in medical, dental and graphic arts. In the medical and dental fields, apparatus is required for developing photosensitive material and in particular X-ray film. In the graphic arts it is usually light sensitive film or light sensitive paper that is to be developed.
In these fields of use it is important for the photosensitive material to pass through the developing apparatus without defects being produced by the developing apparatus in the optical information on the photosensitive material. Such defects can easily occur especially when dirt from the transport system of the apparatus is transferred to the photosensitive material. The transport system of such apparatus usually comprises pairs of rollers between which the sheet-form photosensitive material passes. Of such pairs of rollers usually about 40 percent are located above the liquid level in the apparatus while the remaining 60 percent are below the liquid level. Crystallized chemical residues, gelatin, silver, lime and other impurities from the water are deposited on the rollers. This occurs especially on the upper rollers when the machine is switched off and these rollers become dry.
On the morning when the developing apparatus is started up these dirt particles are picked up by the first photosensitive material being processed and thereby produce, for example on an X-ray film, patterns which are actually not present. Especially in the medical and dental fields such misinformation is not acceptable.
In order to avoid such defects it has been proposed to pass one or two cleaning films through the apparatus when it is first started up after standing idle for a long time. In this manner the roller pairs are cleaned by the relatively thin emulsion layer of the film. Such cleaning films can ordinarily be used only since the emulsion on the surface is so hardened by the fixing bath and the drying that if the film is used again the desired cleaning of the rollers is not effected.
Such previously used cleaning films are relatively expensive as these are for example films having a relatively high silver content. There are also on the market plastic films for use in cleaning the rolls of developing apparatus instead of the silver-containing cleaning film. However, the cleaning effected by such plastic films has not been found to be satisfactory.